What is the recommended diagnostic approach, isolation precautions, and treatment—including antiviral therapy and post‑exposure vaccination—for a patient with suspected monkeypox (Mpox)?

Mpox: Diagnostic Approach, Isolation, and Treatment

For suspected Mpox, immediately isolate the patient with contact and droplet precautions, obtain PCR testing from skin lesions for diagnosis, provide supportive care as first-line treatment, and offer tecovirimat for severe or immunocompromised cases, while administering post-exposure vaccination (JYNNEOS preferred) within 4-14 days of exposure for high-risk contacts.

Diagnostic Approach

The diagnosis of Mpox requires a high index of suspicion in patients presenting with characteristic features:

Clinical Recognition

Look specifically for:

• Skin lesions progressing through distinct stages: macules → papules → vesicles → pustules over 2-4 weeks 1
• Lymphadenopathy (56-86% of cases)—this is the key distinguishing feature from smallpox 1
• Prodromal symptoms: fever (62-72%), myalgias (31-55%), malaise (23-57%), headache (25-55%) 1
• Exposure history: intimate/sexual contact, travel to endemic areas, or contact with confirmed cases

Laboratory Confirmation

PCR testing of lesion specimens is the gold standard 1, 2. Collect samples by:

• Swabbing the base of vesicles or pustules
• Testing multiple lesions if possible
• Supplementary methods include virus isolation, serology, and electron microscopy, but PCR remains preferred 2

Isolation Precautions

Implement immediate contact and droplet precautions based on smallpox transmission principles 3:

• Isolate patients until all lesions have crusted and separated (typically 2-4 weeks) 1
• Use standard, contact, and droplet precautions (gown, gloves, N95 respirator, eye protection)
• Place in single-patient room with negative pressure if available
• Limit healthcare worker exposure—assign dedicated staff when possible
• Critical caveat: Hospital-based transmission accounted for >50% of spread cases during historical smallpox outbreaks 3, making strict infection control essential

Treatment Strategy

First-Line: Supportive Care

Most cases are self-limited and require only symptomatic management 1:

• Skin care and wound management
• Analgesics for pain control
• Hydration and nutritional support
• Monitor for secondary bacterial infections

Antiviral Therapy Indications

Consider tecovirimat (TPOXX) for:

• Severe disease (extensive lesions, mucosal involvement)
• Immunocompromised patients, especially HIV with CD4 <200 cells/μL (mortality risk <0.2% overall but significantly higher in this group) 1
• Pregnant women
• Children
• Complications (encephalitis, ocular involvement)

Alternative antivirals available through expanded access: brincidofovir, cidofovir, and vaccinia immune globulin intravenous (VIGIV) 1, 2

Important limitation: No FDA-approved treatments exist specifically for Mpox; these are available through expanded access programs or clinical trials 1

Post-Exposure Vaccination

Administer JYNNEOS (Modified Vaccinia Ankara-Bavarian Nordic) vaccine as post-exposure prophylaxis:

Timing and Efficacy

• Optimal window: Within 4 days of exposure for prevention
• Extended window: 4-14 days post-exposure may reduce disease severity 1
• Efficacy: 66-86% protection with 2-dose series 1

Priority Groups for Vaccination

• Healthcare workers with unprotected exposure
• Household and intimate contacts of confirmed cases
• Individuals with high-risk sexual exposures (particularly men who have sex with men during outbreaks) 1

Vaccine Selection

JYNNEOS is strongly preferred over ACAM2000 2, 4 because:

• Non-replicating vaccine (safer profile)
• Can be used in immunocompromised individuals
• Safe for pregnant women
• No risk of inadvertent inoculation or transmission to contacts

ACAM2000 contraindications include: immunocompromised patients, eczema/atopic dermatitis, pregnancy, breastfeeding, age <1 year, and household contacts with these conditions 5

Surveillance and Contact Tracing

Implement surveillance and containment strategy (proven effective during smallpox eradication) 3:

• Identify and isolate cases immediately
• Trace and vaccinate primary contacts (direct exposure)
• Monitor and potentially vaccinate secondary contacts (contacts of primary contacts)
• Daily symptom monitoring for 21 days post-exposure

Critical Pitfalls to Avoid

1. Do not delay isolation while awaiting test results—isolate on clinical suspicion
2. Do not use ACAM2000 in immunocompromised patients or those with eczema—use JYNNEOS only
3. Do not assume low transmission risk—hospital transmission was responsible for half of historical poxvirus spread 3
4. Do not overlook HIV testing in Mpox patients, as advanced HIV significantly increases mortality risk 1
5. Do not miss the vaccination window—efficacy decreases substantially after 4 days post-exposure